Ink jet recording methods are printing methods by which ink droplets are ejected and made to adhere on recording media such as paper. Due to recent innovative advancement in ink jet recording technologies, ink jet recording methods are being increasingly employed in the fields of high-definition printing that has been realized by silver halide prints and off-set printing heretofore. With this advancement, inks for ink jet recording have been developed that can produce images having glossiness comparable to silver halide prints by ink jet recording using highly glossy recording media, i.e., special paper, comparable to the developing paper, art paper, and the like that have been used in the fields of silver halide photos and off-set printing. Moreover, inks for ink jet recording that can achieve image quality comparable to silver halide photos even when normal paper is used have also been developed.
Due to recent widespread of image-forming technologies using digital data, desk top publishing (DTP) has become popular in the fields of printing in particular. Even when printing is performed through DTP, a proof for correcting color is produced beforehand to confirm the gloss and color of actual prints. Ink jet recording methods are being applied to outputting of such proofs. In DTP, color and stability of prints must be reproduced; thus, special paper for ink jet recording is normally used as recording media.
Special paper for ink jet recording is made such that a print has the same gloss and color as those of an actually output print on printing paper. As such, the quality and material for special paper are appropriately adjusted according to the type of printing paper but it increases the production cost to make special paper that is compatible to all varieties of printing paper. Thus, for color proof usage, it is desirable if ink jet recording can be performed on printing paper rather than special paper. If samples made by performing ink jet recording directly on printing paper without using special paper can be used as the final proof samples, possibly, the cost required for proofing can be dramatically saved. Moreover, synthetic paper prepared by mixing inorganic fillers and the like with polyethylene resins or polyester resins and forming the resulting mixtures into films is widely used in the field of printing and is attracting attentions as environmentally friendly products that have high recyclability.
Printing paper is coated paper having a coating layer for receiving oil-based inks on its surface and is characterized in that the coating layer has poor ink-absorbing property for water-based inks. Thus, when water-based pigmented inks commonly used in ink jet recording are used, the inks exhibit low permeability into the recording medium (printing paper) and ink bleeding or uneven aggregation may occur in the images.
To address the problem described above, for example, Japanese Unexamined Patent Application Publication No. 2005-194500 (Patent Document 1) discloses a pigment-based ink that reduces bleeding and exhibits excellent glossiness on special paper, in which a polysiloxane compound is used as a surfactant and an alkanediol such as 1,2-hexanediol is used as a dissolving aid. Japanese Unexamined Patent Application Publication No. 2003-213179 (Patent Document 2), Japanese Unexamined Patent Application Publication No. 2003-253167 (Patent Document 3), and Japanese Unexamined Patent Application Publication No. 2006-249429 (Patent Document 4) propose that high-quality images can are obtained by controlling the permeability of inks into recording media through addition of glycerin, a diol such as 1,3-butanediol, or a triol alcohol solvent such as pentanetriol to inks.